Rheostat switch



April 17, 1934. w. o. DENNIS RHEQSTAT SWITCH Filed Oct. 27. 1930 2Sheets-Sheet, 1

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April 1934- w. o. DENNIS 1,955,227

mmosm'r swrrcn Filed Oct. 27, 1930 I 2 Sheets-Sheet, 2

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A TTORNEY Patented Apr. 17, 1934 PATENT OFFICE UNITED STATES ,22 mosm'rswrrcn William 0. Dennis, km City, it.

Application mm 21, 1930, Serial No. 491,021

Claims. (01. zoo-oz) This invention relates to electric switches, andmore particularly to an automatic rheostat switch adapted for remoteoperation in controlling electric circuits, vfor example, a circuitcontrolling a 5 slip ring induction type motor; the principal object ofthe invention being to provide a positively operated switch ofsimplified and compact construction for controlling of comparativelyheavy electric currents.

Another object of the invention is to provide a switch wherein theoperating mechanism may be readily removed from its panel for repairs orreplacement without disturbing electrical connections or other wiring.

In accomplishing these and other objects of the invention, I haveprovided improved details of structure, the preferred forms of which areillustrated in the accompanying drawings, wherein:

Fig. 1 is a front elevational view of a rheostat switch constructed inaccordance with my invention.

Fig.2isaverticalsectionalviewthroughflie switch on the line 2-2, Pig. 1.

Fig.3isa viewillustratingcircuits for remotely controlling the switch,as connected in circuit with a slip ring induction motor.

Referringmoreindetailtothedrawina:

The switch illustrated is particularly for controlling operation of athree phase slipringinductiontypemotorandincludesafixed panel 1preferably formedof insulating material,sothatthecontactsaudotherwiringforcontrollingamotorcircuitmaybedirectlymmmtedthereon, which, in the present instance, includesthreeseriesofspacedcontactpla i 2,3,and4,andconnectedcontactstrips5,6and'Lwiththerespectiveseriesofcontacts for connectingelements 10, 11and12into the motor circuit as later described.

The contact platesofoneseriesaremountedontheponelintwiththecontactplatesofeachoftheotherseriesbyscrewslilextendmgthroughtheplatesandintothepanel.Thecontactstripsarecoextenslvewiththeseriesofcontactplatesandaremoimtedonthepanelbyscrewsiiextendingthroughtheendsoftbestflps asshowninl'ig. 1. I

Supportedadjaeenttheupperandloweredges oi-the panel and extendinglongitudinally of the seriesofcontactsarerailsortracksl5andl6preferablycomprisingrodshavhiglaterallybentends1'IprovidedwithdImlders18thefaceofthepanelandthreadedterminalswhichextendthroughthepanelandaresecuredther'etobynutslflthradedontheextensionstodrawtheshoulders tlghtagainsttheface of thepanel.Thetrackslfiandlfiarethusspacedfromthefaceofthepanelbythelateralextensionsl'lto te switch m now described.'Mountedonthetracks15and16audadapted 00 tomove therealong'overthecontactsisacarrlage 20 preferably comprising -a rectangular plate 21 ofinsulating materialextendingfrom thetoptothebotwmofthepaneLasbestillustratedin Fig. 1. Rotatably mounted on thelower ends of 66 theplatearegroovedrollersnadaptedtobearontheuppersideofthetrack16,andflxedtotherearoftheplateatitsupperendarerearwardly extending brackets 23carrying grooved rollerszlforengagingtherearfaceofthetrack 15, asillustrated in Fig. 2. The carriage, including the plate 21,isthusmounted forrollingmovementonthetracksandmaybereadilydetachedtherefrombyraisingthelowerendoftheplatetoremovetherollersziifroment II with thelowertrack 16, afterwhichtherollers 24maybeunhookedfromtheuppertrack15.

on the rear side oi ductlongearingddoforactuatingagear 41iixedmashaft42projectingfmmtherear imoithcplatezLandwhichmesheswitha no plate21 by rack bar 43 fixed to the front side of the switch panel adjacentthe lower track 16. Thus it is apparent that when the motor 34 isenergized, the pinion 39 will actuate the transmission gearing 40 torotate the gear 41 and cause it to roll along the rack bar to move thecarriage on the tracks 15 and 16 and connect the contact plates inseries with their respective contact strips, thereby cutting outresistance in the motor circuit or adding resistance, depending on thedirection of travel of the carriage.

In order to stop the motor and prevent coasting of the armature when themotor circuit is broken as later described, I provide the armature shaft37 with a cone-shaped disk 44 which is normally urged into brakingengagement with a complementary-shaped brake flange 45 fixed to the acoil spring 46 sleeved on the armature shaft and having one end bearingagainst the pinion 39 and its opposite end against the motor carriageplate 21, so that when the brake disk is in engagement with the fixedmember 45 the spring 46 draws the armature of the motor from the centerof its field and when the circuit to the motor is again closed,energization of the motor field will cause shifting of the armature torelease braking action of the disk 44.

Supported by the carriage plate 21 above the motor is a reversing switchindicated in Figs. 1 and 2 by the housing designated 47 in Figs. 1 and2, whereby the current through the armature may be reversed to changedirection of rotation of the motor and consequently direction of travelof the carriage. The switch 47 preferably includes a bell crank lever 48(Fig. 3) pivotally mounted by apin 49 on the front face or the plate 21,and having an upwardly projecting arm 50 provided with mercury tubeswitch receiving seats 51 and 52. The other arm of the bell crank lever53 is connected by a link 54 with an arm 55 Ma second bell crank lever56 pivotally mounted by a pin 57 projecting from the plate at a pointbelow the pin 49 which mounts the bell crank lever 48. I The other arm58 of the second bell crank lever 56 depends downwardly and can'ies aweighted armature 59 operable between a pair of electromagnets 60and'61. The magnets 60 and 61' include U-shaped pole pieces 62 and 63having magnet coils 64 and 65 so that when the magnet 54 is energized aslater described, the armature 58 will be drawn toward themagnet 60 toswing the bell cranks in one direction, and when the other magnet isenergized the armature will be actuated to move the bell cranks in theopposite direction for closing and opening circuits to the carriageactuating motor 34 as now described.

Supported in the seats 51 and 52 are mercury tube switches 66 and 67,each having a central pocket 68- ior retaining a quantity of mercury 69when the mercury tube switches are in horizontal position, i. e., whenboth'magnets are deenergized and the armature 59 depends by gravitybetween the magnets 60 and 6l,'at which point all circuits to theactuating motor are open, the mercury being adapted to flow from thepockets to close the circuits when either of the coils is energized. Themercury tube switch 66 is provided in its opposite ends with pairs ofterminals 70-71 and 72-73, and the mercury tube switch 67 is alsoprovided with similar terminals 74-75 and 76-77, which terminals 70-71and 74-75 are adapted to be connected by the mercury to close circuitsto operate the motor in one direction, and the terminals 72-73 and 76-77are adapted to reverse the current to operate the motor in the oppositedirection as now described.

Fixed to the switch panel and extending parallel with the contactspreviously described are laterally spaced contact strips 78, 79, 80 and81 for conveying current to the actuating motor 34 and the magnet coilsthrough brushes 82, 83, 84 and 85, respectively, which are carried onthe bar 27 similarly to the brushes previously described.

86, 87 and 88 designate the line wires of a three phase electric circuitand connected with the line 87 is a wire 89 for supplying current to thecontact strip 81 and through the strip to the brush connected by a wire90 with the terminals 75 and 76 of the mercury tube switch 67, the wire90 being connected in series with one of the windings 91 of the carriageactuating motor 34.

Connected with the supply line 86 is a conductor 92 for adaptingcompletion of the circuit through the contact strip 78, brush 82 and aconductor 93 connecting the terminals 71 and 72 of the other mercurytube switch 66.

The terminal 70 of the mercury tube switch 66 and the terminal 77 of themercury tube switch 67 are connected together by a conductor 94 which isconnected to one of the brushes of the motor 34 by a conductor 95. Theremaining terminal 73 of the mercury tube switch 66'is connected by aconductor 96 with the remaining terminal 74 of the mercury tube switch67 which in turn is connected to the other brush of the motor 34 by aconductor 97.

Thus when the mercury tube switches are tipped to the right (Fig. 3),the mercury closes circuit through the terminals 72 and 73 01 themercury tube switch 66 and through the to nals 76 and 77 of the mercurytubeswitch 67 thereby completing circuit from the line wire 87 throughconductor 89, contact strip 81, brush 85, conductor 90, field winding91, terminals 76 and 77, conductor 95, armature of themotor 34,conductor 97, terminals 72 and 73 of the mercury tube switch 66, line93, the other field winding 98 of the motor 34, brush 82, contact strip78, line wire 92 to the feed line 86, energizing the motor to move thecarriage over the series of contacts 2, 3 and 4 to cut out resistanceelements 10, 11 and 12, V

The motor 34 will continue to move the carriage across the contactsuntil all of the resistances are out of circuit, at which point themotor may be reversed by tipping the'mercury tube switches in theopposite. direction to break the circuit through the terminals 72-73 and76-77 and establish circuit through the terminals 70-71 and 74-75,reversing direction of current through the armature of. the motor 34 tocause the motor to rotate in reverse direction and return the carriageover the contacts to again out 135 in the resistances, the circuit beingthen completed through the line 89, brush 85, conductor 90, armaturewinding 91, mercury tube switch terminals 75 and 74, line 97, motorarmature 34, conductor 95, terminals 70 and 71, conductor 140 93, fieldwinding 98, brush 82, conductor 92 to the lead line 86, thus reversingdirection of flow through the motor armature 34.

In order to energize the solenoids 64 and 65 remotely of the the mercurytube switches, I provideplsh buttons 99 and 100 connected in circuit tothe magnets through the bars 79 and 80, as now described.

The push button 99 is Ior'operating thesolenoid 64 tomove the carriageto the right in cut- 150 switch for effecting operation of ting out theresistances and closes circuit through the conductor 92, a conductor 101connecting the push button with the wire 92 and the push button withthe'contact strip '79 to supply current to the brush 83 which isconnected to the coil 64 by a conductor 102. The other lead 0! the coil64 is connected by-a conductor 103 with the conductor to complete thecircuit. 7

The push button is also connected to the conductor 92 and to thecontactstrip 80 by a conductor 104 supplying current to the brush 84 which isconnected to one of the leads of the coil 65 by conductor 105 and theotherv lead oi the coil is.

connected to the conductor 103 to complete the circuit for that coil.

In order to stop movement of the carriage when it approaches the righthand end of the switch panel, the contact strip '79 terminates short ofthe other contact strips to break the motor circuit when the brushesoperating on the series of contacts are moved onto the last contact, atwhich point all of the resistances are out of circuit.

In order to stop movement of the carriage in the opposite direction thecontact strip 80 is shortened in like manner, and in order to preventmisalignment of the brushes I provide dead contacts 105 and 106 at theterminals 01 the strips to retain the brushes in position.

The resistances of a switch constructed as described are connectedtogether at their left hand ends and the other ends are connectedrespectively by leads 107, 108 and 109 with the armature terminals or aslip ring motor which is to be controlled by the switch, and which isdesignated 110 in the drawings, the field winding of the motor beingsupplied from the wires 86, 8'1 and 88.

In operating a switch constructed and assembled as described, assumingthat the carriage is positioned at the left hand side of the switchpanel with all of the resistances in circuit, the operator will closethe circuit to the magnet coil 64 by pushing the button 99 so that acircuit is completed from the lead line 86, conductor 92, push button99, contact strip '79, brush 83, conductor 102, magnet 64, conductors103 and 90, brush 85, contact strip 81, conductor 89 to the other linewire 8'7.

Energization of the coil 64 attracts the armature 99 of the magnet tocause the bell crank levers 48 and 56 to tip the mercury tube switchesand close circuit between the terminals '72-'73 and '76-'77, therebyenergizing the motor 34 to move the carriage across the contacts, thecircuit being established through the lead line 86,

conductor 92,.contact strip '78, brush 82, conductor 93, motor winding98, terminals '72-'73, conductor 96, motor armature, conductor 95,terminals '7'7 and 76, conductor 90, field winding 91, brush 85, contactstrip 81, conductor 89, and lead line 8'7.

The carriage will continue to move across the contacts until the brush83 rides oi! the contact strip '79 or until the operator breaks thecircuit by removing his finger from the push button 99, movement of thecarriage gradually cutting out the resistance from the motor circuituntil the motor is operating at its maximum or an intermediate speedselected by the operator.

Breaking of the circuit by the push button 99 will cause deenergizationoi the magnet coil 64 to permit the armature 58 to swing away from themagnet field pole pieces 60, thereby swinging the mercury tube switchesinto horizontal position to break circuit between the mercury tubeswitch terminals to effect deenergization o! the motor windings 91 and98, whereupon the spring 46 will draw the armature o! the motor out ofalignment with the center of the field winding and cause engagement ofthe brake disk 3'7 with the brake band 45 to prevent coasting oi thecarriage over the selected contacts. 7

If the operator then desires to increase the speed of the motor he willagain close circuit through the push button 99 to continue forwardtravel of the carriage, but should he desire to reduce the speed of themotor he will close circuit through the magnet coils 85 by operating thepush button 100 which establishes circuit through the-conductor 93,conductor 104, contact strip 80, brush 84, conductor 105, magnet coil85', conductor '103, brush 85, contact strip 81, conductor 89. the linewire 8'7.

'Energization o! the coil 65 causes the pole pieces of .the magnet 61 toattract the armature. thereby swinging the mercury tube switches inreverse direction to close circuit through the terminals '70-'71 and'74-'75, Circuit is then established through the motor 34 with thecurrent flowing in through the armature in reverse direction, to reversedirection of rotation, thereby bringing more or the resistances into thecircuit wires 107, 108 and 109, the circuit to the motor 34 beingestablished through conductor 92, contact strip '78, brush 82, conductor93, held winding 98, terminals '71-'70, conductor 94, conductor 95,motor armature, conductor 9'7, terminals '74-'75, conductor 90, fieldwinding 91, brush 85, contact strip 81, conductor 88, and lead line 8'7.

When the motor has been reduced to the de- 110 sired speed the operatorwill remove his finger from the push button 100 to break circuit to themagnet coil 65, allowing the mercury tube switches to return to normalposition and breaking circuit to the terminals '71-'72 and '74-'75,thereby stopping operation or the motor 34.

Attention is directed to the fact that as soon as circuit is establishedthrough the motor field windings 91 and 92, the armature of the motorwill be drawn into the center or the field to re- 180 lease the brakeelements to permit rotation of the motor, but when the circuit isinterrupted to the field windings the spring 46 will again apply thebrake to stop rotation of the motor and prevent coasting ot the carriageover the selected contacts.

While I have described the invention as being employed in connectionwith a slip ring induction type motor, it is apparent that a switchconstructed as described may be used for con- 180 trolling any circuitwherein a rheostat switch is employed. and I do not wish to be limitedto the specific arrangement described.

What I claim and desire to secure by Letters Patent is: I

1. In a rheostat switch of the character described, a panel having aseries oi electric contacts and a cooperating contact strip extendingacross its face, rails-extending longitudinally of the panel adjacentopposite side edges thereor, a circuit closing unit mounted on the railsand movable across the contacts including a carriage, means on thecarriage controlling circuits through said contacts and contact strip, amotor on the carriage and operable to move the carriage along saidrails, and "a reversing mechanism on the carriage controlling the motor.

2. In a rheostat switch 0! the character described, a panel having aseries of electric contacts and a cooperating contact strip extending Iacross its face, rails extending longitudinally of contacts, a rack baron the panel and extending the panel, a carriage removably mounted onthe longitudinally of the'rails, a motor 'on the carrails, means on thecarriage controlling circuits riage, means gearing the motor to saidrack through said contacts, a motor on the carriage bar for moving thecarriage along the rails, 're- 5 and operable'to move the carriage alongsaid versing mechanism on the'carriage for controlrails, a reversingmechanism on the carriage for ling the motor, contact strips on thepanel supcontrolling the motor, contact strips on'the panel plyingcurrent to said motor, and brushes on supplying current to said motor;and brushes on the carriage contacting said strips and operably thecarriage contacting said strips and operably wired to said reversingniecham'sm and said wired to said reversing mechanism and said momotorso that the carriage is removable from tor so that the carriage and itsoperating mechthe panel without afiecting the wiring.

anismare removable as a ,unit for'replacement 5. A rheostat switch, apanel having electric with another unit without afiectingthe wiring.contacts extending across itsface, rails extend- 3. A rheostat switch, apanel having electric ing across'the top andbottonr of the panel, a scontacts extending across its face, rails extendcarriage removablymounted onsaid rails, means ing longitudinally at the top and bottom ofthe on the carriage controlling circuits through the panel, a carriagemovable over said contacts contacts, a rack bar on the panelandextending rollers operable on said rails to support thecarlongitudinally of the rails, a motor on the carriage, means on thecarriage controlling circuits riage, means gearing the motor to saidrack bar 120 through said contacts, a motor on the carriage for movingthe carriage along the rails,'reversing operable to move the carriagealong said rails, a mechanism on the carriage for controlling thereversing mechanism on the carriage for conmotor, contact strips on thepanel supplying curtrolling the motor, contact stripsonthe 'panel rentto said motor, brushes onthe carriage consupplying current to saidmotor, and brushes on tacting said strips and operably wired to saidthecarriage contacting said strips and operably reversingmechanism andsaid motor so that the I wired to said reversing mechanism and said mo-.carriage is removable from the panel without tor so that the carriage isremovable from the afiecting the wiring, and braking mechanism railswithout afiecting the wiring. I I associated with said gearing andoperable auto- 4. A rheostat switch, a panel having electric maticallyupon operation of the reversing mechcontacts extending across its face,rails extendanism to prevent coasting of the carriage on the 1 ingacross the top and bottom of the panel, a rails. carriage removablymounted on said rails, means WILLIAM O. DENNIS. on the carriagecontrolling circuits through the H I i I g I 1;

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